U.S. patent number 11,187,460 [Application Number 16/633,299] was granted by the patent office on 2021-11-30 for device and method for reinforcing recycled aggregate based on in-situ c-s-h production.
This patent grant is currently assigned to SHANDONG UNIVERSITY. The grantee listed for this patent is SHANDONG UNIVERSITY. Invention is credited to Yufeng Bi, Yujie Feng, Xuechi Gao, Zhi Ge, Yanhua Guan, Xinlei Hu, Yanqiu Hu, Jin Qin, Renjuan Sun, Yikai Wang, Jiajie Wu, Zhichao Xue, Huaqiang Yuan.
United States Patent |
11,187,460 |
Ge , et al. |
November 30, 2021 |
Device and method for reinforcing recycled aggregate based on
in-situ C-S-H production
Abstract
A device and method for reinforcing recycled aggregate based on
in-situ C--S--H production including a first, second, third
chamber, and a blast drier. A spray structure arranged on the top
of the third chamber; the first and second chamber connected to the
spray structure through pumps. A hollowed container arranged at the
bottom of the spray structure. A certain gap reserved between the
bottom of the container and the bottom of the third chamber, the
bottom of the third chamber is provided with at least one drain
outlet; the blast drier connected to the bottom of the third
chamber, and a cover is arranged on the top of the third chamber.
The first chamber contains calcium hydroxide solution. The second
chamber contains a mixed solution of TEOS, water and anhydrous
ethanol. The container is arranged in the third chamber, and the
container is used to contain to-be-treated recycled aggregate.
Inventors: |
Ge; Zhi (Jinan, CN),
Yuan; Huaqiang (Jinan, CN), Sun; Renjuan (Jinan,
CN), Guan; Yanhua (Jinan, CN), Gao;
Xuechi (Jinan, CN), Bi; Yufeng (Jinan,
CN), Xue; Zhichao (Jinan, CN), Hu;
Yanqiu (Jinan, CN), Feng; Yujie (Jinan,
CN), Wu; Jiajie (Jinan, CN), Hu; Xinlei
(Jinan, CN), Qin; Jin (Jinan, CN), Wang;
Yikai (Jinan, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
SHANDONG UNIVERSITY |
Shandong |
N/A |
CN |
|
|
Assignee: |
SHANDONG UNIVERSITY (Jinan,
CN)
|
Family
ID: |
65192434 |
Appl.
No.: |
16/633,299 |
Filed: |
December 27, 2018 |
PCT
Filed: |
December 27, 2018 |
PCT No.: |
PCT/CN2018/124119 |
371(c)(1),(2),(4) Date: |
January 23, 2020 |
PCT
Pub. No.: |
WO2020/093560 |
PCT
Pub. Date: |
May 14, 2020 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
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US 20210231371 A1 |
Jul 29, 2021 |
|
Foreign Application Priority Data
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|
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Nov 9, 2018 [CN] |
|
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201811331818.6 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B
20/12 (20130101); C04B 20/023 (20130101); F26B
25/08 (20130101); F26B 21/02 (20130101); C04B
18/167 (20130101); C04B 20/12 (20130101); C04B
18/16 (20130101); C04B 20/1051 (20130101); C04B
20/12 (20130101); C04B 18/16 (20130101); C04B
20/1066 (20130101); Y02W 30/91 (20150501) |
Current International
Class: |
F26B
21/02 (20060101); C04B 20/02 (20060101); F26B
25/08 (20060101); C04B 18/16 (20060101) |
Field of
Search: |
;34/222 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3003605 |
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May 2017 |
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CA |
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203319869 |
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Dec 2013 |
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CN |
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104058622 |
|
Sep 2014 |
|
CN |
|
105174766 |
|
Dec 2015 |
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CN |
|
106277883 |
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Jan 2017 |
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CN |
|
106495516 |
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Mar 2017 |
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CN |
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107382114 |
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Nov 2017 |
|
CN |
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WO-2017079468 |
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May 2017 |
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WO |
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Other References
Aug. 1, 2019 International Search Report issued in International
Patent Application No. PCT/CN2018/124119. cited by applicant .
Aug. 1, 2019 Written Opinion of the International Searching
Authority issued in International Patent Application No.
PCT/CN2018/124119. cited by applicant.
|
Primary Examiner: Gravini; Stephen M
Attorney, Agent or Firm: Oliff PLC
Claims
What is claimed is:
1. A device for reinforcing a recycled aggregate based on in-situ
C--S--H production, the device comprising: a first chamber, a
second chamber, a third chamber, and a blast drier, wherein the
first chamber, the second chamber, and the third chamber are
sealed; a spray structure is arranged at a top of the third
chamber, the first chamber and the second chamber are connected to
the spray structure through pipes and pumps, a container with
hollowed walls is arranged on a bottom of the spray structure,
hollowed portions of the hollowed walls are smaller than a grain
size of the recycled aggregate, a certain gap is reserved between a
bottom of the container and a bottom of the third chamber, the
bottom of the third chamber is provided with at least one drain
outlet; and the blast drier is connected to the bottom of the third
chamber, and a cover is arranged on a top of the third chamber.
2. The device according to claim 1, wherein a plurality of spray
heads is arranged on the spray structure, and a spray area of the
spray heads uniformly covers a cross section of the container.
3. The device according to claim 1, wherein two gas distributors
are located between the blast drier and the third chamber, and the
two gas distributors are symmetrically arranged on two sides of the
third chamber.
4. The device according to claim 1, wherein the device for
reinforcing recycled aggregate based on in-situ C--S--H production
further comprises a vacuum device which connects to the third
chamber.
5. The device according to claim 4, wherein two connection points
are arranged between the third chamber and the vacuum device, and
the two connection points are symmetrically arranged relative to
the third chamber.
6. The device according to claim 1, wherein there are two drain
outlets, which are respectively connected to the first chamber and
the second chamber.
7. A method for reinforcing a recycled aggregate based on in-situ
C--S--H production, the method comprising: 1) sieving the recycled
aggregate to remove waste particles in the recycled aggregate, and
removing mud and incompletely stripped mortar on a surface of the
recycled aggregate; 2) loading the recycled aggregate into a
container after cleaning the recycled aggregate, and placing the
container in a third chamber; 3) switching on a blast drier,
switching off the blast drier after the recycled aggregate in the
third chamber is dried, and then switching on a vacuum device to
vacuumize the third chamber; 4) conveying a mixed solution of
anhydrous ethanol, water and tetraethoxysilane (TEOS) into a spray
device of the third chamber; evenly spraying the mixed solution
onto the recycled aggregate by the spray device; and after a first
period of soaking, discharging out the mixed solution and switching
on the blast drier to dry the recycled aggregate; 5) switching on
the vacuum device to vacuumize the third chamber; 6) conveying a
calcium hydroxide solution into the spray device on the third
chamber; evenly spraying the calcium hydroxide solution onto the
recycled aggregate by the spray device; and after a second period
of soaking, discharging out the calcium hydroxide solution and
switching on the blast drier to dry the recycled aggregate.
8. The method according to claim 7, wherein, in step 4), a molar
ratio of anhydrous ethanol to water to TEOS is
3.5-4.5:1:2.5-3.5.
9. The method according to claim 8, wherein the second period of
soaking is 10 to 20 h.
10. The method according to claim 7, wherein, in step 6), the
calcium hydroxide solution is a saturated calcium hydroxide
solution; and the second period of soaking is 10 to 20 h.
Description
BACKGROUND
Technical Field
The present invention relates to the technical field of recycled
concrete aggregate, and in particular to a device and a method for
reinforcing recycled aggregate based on in-situ C--S--H
production.
Related Art
In recent years, with the constant progress of the Chinese society
and the rapid development of science, technology and economy, China
has been striving to develop infrastructures. The civil buildings
and mileage of roads and highways are rapidly increasing. As a
construction material with high bearing capability and excellent
performance, concrete has been widely applied in civil and
transportation engineering. China consumed about 2 billion cubic
meters of commercial concrete in 2017. As an important raw material
for concrete production, natural sand and gravel are unrenewable
resources. In the past, as natural sand and gravel were wide in
resource and low in price, they were wantonly mined, and as a
result, high-quality natural sand and gravel are becoming short
nowadays. Yet, in the future all industries still have a tremendous
demand on concrete and will consume a gigantic amount of
high-quality natural sand and gravel due to the development of the
society, so we have to seek some new materials to replace natural
sand and gravel in order to save and protect the resources. In
another aspect, in the progress of urbanization, about two hundred
million square meters of old buildings are demolished per year in
China, producing about four hundred million tons of construction
and demolition (C&D) waste, which accounts for 30% to 40% of
the total amount of urban waste and 50% to 60% of which is waste
concrete. Most of the building waste is land filled so it not only
occupies the valuable space but also causes environmental concerns.
With proper approach, C&D waste could be used to produce
recycled aggregate. Recycling C&D waste could resolve both
issues of waste pollution and shortage of natural resources.
Therefore, researchers had conducted a lot of studies on recycled
aggregate. In particular, a technology for producing concrete with
recycled concrete from C&D waste has tremendous social,
environmental, and economic benefits, and is a hot topic that
various countries in the world are concerned about. In 1950s, the
Soviet Union and Germany carried out researches on recycled
concrete technology in succession. In 1976, the International Union
of Laboratories and Experts in Construction Materials, Systems and
Structures (RILEM) established the Technical Committee 37-DRC
(Demolition and Reuse of Concrete) (TC-37-DRC) to start the
research on the treatment and recycling of waste, and moreover, in
1982, a conference with the topic of producing recycled concrete
with recycled aggregate was held in Copenhagen. Japan was the first
country in the world to recycle waste concrete. It has established
numbers of laws and regulations and built factories for treating
building waste to ensure the recycling of building waste. The
recycling rate of building waste has reached over 98%. Countries,
such as America, Netherlands, Denmark, etc. have also enacted
relevant laws and regulations. Compared with some developed
countries, China started the research on recycled concrete
relatively late due to sufficient natural sand resource, but has
also made a lot of achievements. Many experts and scholars in China
have made a large number of researches on the improvement of the
physical properties, mechanical properties, structural properties
and so on of recycled concrete.
At present, research in China mainly focuses on the properties of
recycled concrete, but there are few researches on recycled
aggregate. However, the properties of recycled aggregate affect the
properties of concrete significantly. Due to the large variation of
properties of recycled aggregate and sources, direct use will lead
to the great variation of recycled concrete. Typically, the large
crush machine is adapted to produce recycled aggregate. The machine
could gradually reduce the grain size of the recycled aggregate and
remove the old mortar from the aggregate. However, this process
will also cause micro-cracks inside aggregate. In addition, because
the crushed recycled aggregate still contains a great deal of
cement mortar and a lot of micro-cracks formed in the process of
crushing, not only is the strength of the aggregate decreased, but
also the recycled aggregate has the characteristics of high
porosity, high water absorption rate, high water absorption speed,
etc. These will cause adverse influence on the workability,
mechanical properties and durability of the recycled concrete.
SUMMARY
On the basis of producing in-situ C--S--H, the present invention
provides a device and a method for reinforcing recycled aggregate
to solve the issues related with high variation, low strength and
high water absorption of recycled aggregate.
In order to solve the aforementioned technical problems, the
technical solution of the present invention is as follows:
A device for reinforcing recycled aggregate based on in-situ
C--S--H production comprises three sealed chambers, namely a first
chamber, a second chamber and a third chamber, and a blast drier,
and the first chamber, the second chamber and the third chamber are
sealed.
A spray structure is arranged on the top of the third chamber. The
first chamber and the second chamber are connected to the spray
structure through pumps. A container with hollowed walls is
arranged on the bottom of the spray structure. The hollow is
smaller than the grain size of the recycled aggregate. A certain
gap is reserved between the bottom of the container and the bottom
of the third chamber. The bottom of the third chamber is provided
with at least one drain outlet.
The blast drier is connected to the bottom of the third chamber,
and a cover is arranged on the top of the third chamber.
The first chamber is used to contain a calcium hydroxide solution.
The second chamber is used to contain a solution mixed with
tetraethoxysilane (TEOS), water and anhydrous ethanol. A container
is arranged in the third chamber to contain to-be-treated recycled
aggregate. The calcium hydroxide solution and the mixed solution
(TEOS, water and anhydrous ethanol) are respectively pumped into
the spray structure on the top of the third chamber by using pumps
and sprayed to the to-be-treated recycled aggregate for the
spraying and soaking treatment. After the mixed solution of TEOS,
water and anhydrous ethanol is absorbed by the recycled aggregate,
in internal voids of the recycled aggregate, TEOS is hydrolyzed to
silica sol with pozzolanic activity which can react with calcium
hydroxide to form calcium silicate hydrate (C--S--H) with gelation
property in the voids within a certain depth range, filling the
internal voids of the recycled aggregate and repairing various
micro-cracks. As all the walls of the container are hollowed, the
sprayed solutions may be conveniently sprayed to soak the recycled
aggregate, and once the soaking process is completed, the solutions
in the container are easily drained off. As a certain gap is
reserved between the bottom of the container and the bottom of the
third chamber, the whole liquid in the container can be
conveniently drained. At this moment, when the blast drier is
switched on to dry the aggregate, the degree of drying can be
easily increased.
Preferably, a plurality of spray heads is arranged on the spray
structure, and a spray area of the spray heads uniformly covers the
cross section of the container.
Preferably, two gas distributors are arranged between the blast
drier and the third chamber, and the two air distributors are
symmetrically arranged on two sides of the third chamber. The blast
drier symmetrically blows drying wind into the third chamber, which
is more favorable for the uniform drying of the recycled
aggregate.
Preferably, the device for reinforcing recycled aggregate based on
in-situ C--S--H production further includes a vacuum device, and
the vacuum device connects to the third chamber.
More preferably, two connection points are arranged between the
third chamber and the vacuum device, and the two connection points
are symmetrically arranged relative to third chamber. The symmetric
arrangement of the connection points can enable the third chamber
to more easily achieve a vacuum negative pressure state to
accelerate the permeation of the solutions into the recycled
aggregate, increasing the efficiency of reinforcing the recycled
aggregate and shortening the time of recycled aggregate
treatment.
Preferably, there are two drain outlets, which are respectively
connected to the first chamber and the second chamber to recycle
the solutions after spray soaking.
A method for reinforcing recycled aggregate based on in-situ
C--S--H production includes the following steps:
(1) removing mud on a surface of recycled aggregate.
(2) loading the cleaned recycled aggregate into a container, and
placing the container into the third chamber;
(3) switching on the blast drier, switching off the blast drier
after the recycled aggregate in the third chamber is dried, and
then switching on a vacuum device to vacuumize the third
chamber;
(4) conveying the mixed solution of anhydrous ethanol, water and
TEOS into a spray device of the third chamber; evenly spraying the
calcium hydroxide solution onto the recycled aggregate by the spray
device; and after a period of spraying and soaking, discharging out
the solution and switching on the blast drier to dry the recycled
aggregate;
(5) switching on the vacuum device to vacuumize the third chamber;
and
(6) conveying a calcium hydroxide solution into the spray device of
the third chamber; evenly spraying the calcium hydroxide solution
onto the recycled aggregate by the spray device; and after a period
of spraying and soaking, discharging out the and switching on the
blast drier to dry the recycled aggregate.
Preferably, in step (4), a molar ratio of anhydrous ethanol to
water to TEOS is 3.5-4.5:1:2.5-3.5.
Preferably, in step (4), the soaking time is 10 to 20 h.
Preferably, in step (6), the calcium hydroxide solution is a
saturated calcium hydroxide solution, and a preparation method of
the calcium hydroxide solution includes: preparing the saturated
calcium hydroxide solution, and slightly separating out calcium
hydroxide.
More preferably, the time of soaking the recycled aggregate in the
calcium hydroxide solution is 10 to 20 h.
The beneficial effects of the present invention are as follows:
As a nano-silicon precursor, TEOS has a small monomer structure and
a low consistence. TEOS can easily permeate into the recycled
aggregate under the drive of vacuum, and is hydrolyzed into silica
sol with the pozzolanic activity, which can react with calcium
hydroxide to form calcium silicate hydrate (C--S--H) with gelation
property in the voids within a certain depth range, filling the
internal voids of the recycled aggregate and repairing various
micro-cracks. Therefore, the compactness of the external surface of
the recycled aggregate is increased, the strength of the recycled
aggregate is increased and the water absorption rate of the
recycled aggregate is decreased. Consequently, the utilization rate
of building waste is increased. Moreover, the properties of
recycled concrete can be improved. Unlike the other methods (such
as the mortar wrapping method) for externally treating recycled
aggregate, the method prevents defects (such as poor bonding or
hollowing and shedding) that may occur during external
treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings of the specification which constitute part of the
present application are used to provide the further understanding
of the present application, and the exemplary embodiments of the
present application and the description thereof are used to explain
the present application, and do not constitute an improper
limitation to the present application.
FIG. 1 is a schematic diagram of the recycled aggregate device in
the present invention;
FIG. 2 is a picture of treated recycled aggregate using the present
invention;
FIG. 3 is a picture of the products in voids of the treated
recycled aggregate;
FIG. 4 is a crushing value test for the recycled aggregate;
FIG. 5 is a water absorption rate graph of the recycled
aggregate;
FIG. 6 is a crushing value graph of the recycled aggregate; and
FIG. 7 is a picture of the crushed recycled aggregate.
In the drawings, 1. Vacuum device; 2. Valve A; 3. Third chamber; 4.
Solution spray device; 5. Valve B; 6. Second chamber; 7. Blast
drier; 8. Valve D; 9. Recycled aggregate container; 10. Valve C;
and 11. First chamber.
DETAILED DESCRIPTION
It should be pointed out that the following detailed description is
illustrative, and is intended to provide the further description of
the present application. Unless otherwise specified, all the
technological and scientific terms used herein have the same
meanings as generally understood by those of ordinary skill in the
art covering the present application.
It should be noted that the terms used herein are merely intended
to describe the specific embodiments rather than limit the
exemplary embodiments according to the present application. As used
herein, unless otherwise explicitly specified in the context, the
singular form is also intended to include the plural form, and in
addition. It should also be understood that, in the present
specification, the terms "include" and/or "comprise" indicate the
existence of features, steps, operations, devices, components
and/or their combination.
Embodiment 1
The present embodiment can be used for a factory for
mass-reinforcing recycled aggregate based on the in-situ C--S--H
production method, see FIG. 1. The present invention can integrate
a variety of functions, such as cleaning of recycled aggregate,
reinforcement of recycled aggregate, drying of recycled aggregate.
The treated recycled aggregate can be used directly for the
concrete production and its modified strength and water absorption
rate can be kept for a long time. The device for treating recycled
aggregate mainly includes a first chamber 11, a second chamber 6, a
third chamber 3, a vacuum device 1, a solution spray device 4, a
recycled aggregate container 9, and a blast drier 7.
The first chamber 11, the second chamber 6 and the third chamber 3
are connected to each other. A plurality of valves is arranged
between the chambers (FIG. 1), namely valve A2, valve B5, valve D8,
and valve C10. The shape and volume of each chamber are not
limited, but each chamber must have good sealing performance, which
can be used to store solutions. The first chamber 11 is a calcium
hydroxide solution storage chamber, which is connected to the third
chamber 3. The Valve A2 and valve C10 are located on the connecting
pipe. Through this pipe, the calcium hydroxide solution can flow to
the third chamber 3 or back to the first chamber 11 for recycling.
The first chamber 11 can be used for the preparation or replacement
of the calcium hydroxide solution. The second chamber 6 is a
storage chamber for the mixed solution of anhydrous ethanol, water
and TEOS. The second chamber 6 is connected to the third chamber 3,
Valve B5 and valve D8 are designed on the connecting pipe. Through
the connecting pipe, the mixed solution can flow to the third
chamber 3 or back to the third chamber 3 for recycling. The second
chamber 6 can be used for the preparation or replacement of the
mixed solution (the mixed solution of anhydrous ethanol, water and
TEOS). The third chamber 3 is the main reinforcing place for the
recycled aggregate. The to-be-treated recycled aggregate is
sequentially soaked in the mixed solution (the mixed solution of
anhydrous ethanol, water and TEOS), the calcium hydroxide solution
and dried in the third chamber 3.
The vacuum device is arranged at the outside of the third chamber
3. Vacuuming orifices are symmetrically arranged on two sidewalls
of the third chamber 3. The vacuum device is connected to the
vacuuming orifices to vacuumize the third chamber 3. The symmetric
arrangement of the vacuuming orifices can facilitate the third
chamber 3 to achieve a vacuum negative pressure state to accelerate
the permeation of the solution into the recycled aggregate,
increasing the efficiency of reinforcing the recycled aggregate and
shortening the time period for the recycled aggregate
treatment.
The solution spray device is located on the top of the third
chamber 3 and above the recycled aggregate container. Its spraying
area fully covering the recycled aggregate container. It can evenly
spray the solution to the first chamber 11 and the second chamber 6
so that the aggregate can be sufficiently and completely
soaked.
The recycled aggregate container 9 is a cover-less cuboid with a
function of containing the to-be-treated recycled aggregate. Four
sides of the recycled aggregate container are designed to be
hollow. The hollowed parts are smaller than the recycled aggregate.
The bottom of the recycled aggregate container 9 is slightly higher
than the bottom of the third chamber 3 to ensure that the redundant
solution can be gathered to flow back to the first chamber 11 (or
the second chamber 6) via the valve C10 (or the valve D8) after the
sufficient soaking of recycled aggregate through spraying.
The blast drier is arranged on the bottom of the third chamber 3,
and is connected to sidewalls of the third chamber 3 through two
connection points. The two connection points are symmetrically
arranged on the sidewalls of the third chamber 3. The recycled
aggregate in the third chamber 3 can be easily dried.
The specific steps are as follows:
(1) Sieving of recycled aggregate:
The crushed recycled aggregates were sieved using a square hole
sieve. Aggregates having grain size between 9.5 and 13.2 mm were
used for the subsequent test.
(2) Cleaning of aggregate:
The recycled aggregate sieved in step (1) was washed by clean water
to clean the mud or incompletely stripped mortar attached to the
surface of the aggregate. The recycled aggregate was loaded into
the recycled aggregate container 9 after the cleaning. The recycled
aggregate container 9 was then put into the third chamber. All the
valves were closed.
(3) The blast drier 7 in the third chamber 3 was switched on to dry
the recycled aggregate in the third chamber 3.
(4) The blast drier 7 was switched off. The third chamber being
sealed was ensured. The vacuum device 1 was switched on to render
the third chamber 3 under a vacuum negative pressure state.
Afterwards, the vacuum device 1 was switched off.
(5) Preparation of saturated calcium hydroxide solution:
An appropriate amount of clean water was added into the first
chamber 11. Afterwards, calcium oxide powder was slowly added and
constant stirring was performed until the solution became turbid
and precipitates occurred. Then a small amount of calcium oxide was
excessively added.
(6) Preparation of mixed solution of anhydrous ethanol, water and
TEOS:
All the materials were weighed according to the proportion listed
in table 1. All the materials were sequentially added into the
second chamber 6 and gentle stirring was performed to mix the
solution uniformly. The second chamber 6 was sealed to prevent the
volatilization of ethanol.
(7) The valve B5 was opened to convey the mixed solution of
anhydrous ethanol, water and TEOS in the second chamber 6 to the
solution spray device 4 in the third chamber 3. The mixed solution
was then evenly sprayed onto the aggregate at a constant speed.
After the aggregate fully absorbed the mixed solution, the
redundant mixed solution flowed to the bottom of the third chamber
3. The valve D8 was opened. The gathered mixed solution was pumped
back into the second chamber 6 using the pump placed between valve
D8 and the second chamber 6. In this way, the mixed solution could
be recycled continuously. The process of spraying the mixed
solution of anhydrous ethanol, water and TEOS lasted for 12 h.
Vessels must be sealed to prevent ethanol volatizing, which affects
the test result significantly.
(8) After the mixed solution for synthesizing nano-silica based on
a sol-gel method was sprayed for the last time, the mixed solution
was recovered into the second chamber 6, and the valve B5 and the
valve D8 were then closed. The blast drier 7 in the third chamber 3
was switched on to dry the recycled aggregate treated in step
(8).
(9) The blast drier 7 was switched off. The third chamber 3 being
sealed was ensured. The vacuum device 1 was switched on to render
the third chamber 3 under a vacuum negative pressure state. The
vacuum device 1 was switched off.
(10) The valve A2 was opened to convey the calcium hydroxide
solution in the first chamber 11 to the solution spray device 4 in
the third chamber 3, the calcium hydroxide solution is then evenly
sprayed onto the aggregate at a constant speed, and after the
aggregate fully absorbed the calcium hydroxide solution, the
redundant calcium hydroxide solution flowed the bottom of the third
chamber 3. The valve C10 was opened. The gathered calcium hydroxide
solution was pumped back into the first chamber 11 using the pump
placed between the valve C10 and the first chamber 11. In this way,
the calcium hydroxide solution could be recycled continuously. The
process of spraying the calcium hydroxide solution lasted for 12
h.
(11) After the last time calcium hydroxide solution spraying, the
calcium hydroxide solution completely flowed back into the first
chamber 1. The valve A2 and the valve C10 were closed. The blast
drier 7 in the third chamber 3 was switched on to dry the recycled
aggregate treated in step (11).
(12) Test steps (7)-(11) could be repeated according to
requirements.
(13) The treated recycled aggregate in the third chamber 3 was
collected. Their water absorption and crushing values were measured
according to Chinese standard JTG E42--2005.
The treated recycled aggregate is shown in FIG. 2. Products in
voids of the treated recycled aggregate are shown in FIG. 3. Set-up
of crushing value test is shown in FIG. 4. Water absorption rate
and crushing value test results are respectively shown in FIG. 5
and FIG. 6. The crushed aggregate is shown in FIG. 7.
TABLE-US-00001 TABLE 1 Mixture proportion of the mixed solution for
synthesizing nano-silica based on the sol-gel method. Material name
Anhydrous ethanol Distilled water TEOS Proportion 4 1 3
The aforementioned pictures and test data indicate that the
recycled aggregate treatment method provided by the present
invention can remarkably decrease the water absorption of the
recycled aggregate, increase the strength of the recycled aggregate
and decrease the crushing value of the recycled aggregate. It can
be seen in FIG. 4 that the water absorption rate of the recycled
aggregate decreases from 17% to 10%. It decreased by 41% in
comparison with the water absorption rate of untreated recycled
aggregate. It can be seen from FIG. 5 that the crushing value of
the recycled aggregate decreases from 41% before treatment to 33%
after treatment using the method provided by the present invention.
Crushing value of the recycled aggregate decreases by 20%. It can
be concluded that, by using the novel recycled aggregate
reinforcing method, the solutions can effectively permeate into the
aggregate. The C--S--H produced by reaction can fill micro-cracks
and voids in the recycled aggregate so that the compactness of the
surface of the recycled aggregate is increased and the porosity of
the recycled aggregate is decreased. Therefore, the objectives of
decreasing the water absorption rate of the recycled aggregate and
increasing the strength of the recycled aggregate are achieved.
The technological progress achieved by the process and the device
for reinforcing recycled aggregate based on in-situ C--S--H
production using the present invention are remarkable. Through the
simple and easy-to-implement process, the properties of recycled
aggregate can be improved effectively with low economic investment.
Consequently, the working performance, mechanical properties and
durability of recycled aggregate concrete are improved, and the
utilization rate of recycled aggregate is increased.
The aforementioned embodiment is merely a preferred case of the
present application and is not used to limit the present
application. For those skilled in the art, the present application
may have various changes and variations. Any modification,
equivalent replacement, improvement and so on which are made within
the spirit and principle of the present application shall fall
within the protection scope of the present application.
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